1. Field of the Invention
The present invention generally relates to at method, apparatus, and system for negotiation between an access terminal and an access network in a mobile communication system. More particularly, the present invention relates to a method, apparatus, and system for negotiating a session between an access terminal and an access network that can simplify a repeated negotiation procedure when the session is configured/updated/deleted between the access terminal and the access network.
2. Description of the Related Art
With the quick development of communication technologies, mobile communication networks provide a high rate data service for enabling a multimedia service for e-mail, still and moving images, and so on, as well as a conventional voice service. Conventional mobile communication systems for supporting the high rate data service include Code Division Multiple Access 2000 1x (CDMA2000 1x), 1x Evolution Data Only (1xEV-DO), 1x Evolution for Data & Voice (1xEV-DV), asynchronous Universal Mobile Telecommunication Systems (UMTS), and so on. These mobile communication systems have a channel structure for high rate data transmission.
Among these mobile communication systems, the 1xEV-DO system is a high rate packet data system proposed by Third-Generation Partnership Project 2 (3GPP2) for data communication enhancement of an IS-2000 system. First, a channel structure of the 1xEV-DO system will be briefly described.
In the 1xEV-DO system, forward physical channels transmitted from an access network (AN) to an access terminal (AT) include a pilot channel, forward medium access control (MAC) channel, forward traffic channel, and forward control traffic. The forward physical channels are transmitted to the AT in a time division multiplexing (TDM) scheme. A user data packet is transmitted through the forward traffic channel of the forward physical channels. A control message and an encapsulated user data packet are transmitted through the forward control channel corresponding to a common channel. The forward MAC channel is used to transmit reverse rate control information, power control information, and so on.
In the 1xEV-DO system, reverse physical channels transmitted from the AT to the AN are different from the forward physical channels in that the reverse physical channels have different identification codes on an AT-by-AT basis. The AT-by-AT reverse channels are a pilot channel, reverse traffic channel, reverse data rate control (DRC) channel, reverse rate indicator (RRI) channel, access channel, and so on. A user data packet is transmitted through the reverse traffic channel. The access channel is used when the AT transmits a message or traffic to the AN before a traffic channel is connected. The DRC channel is used to notify the AN of the highest transmission rate at which the AT can receive data. The RRI channel is used to give notification of a transmission rate at which data is transmitted through the reverse traffic channel.
On the other hand, the AT is identified using an electronic serial number (ESN) in the conventional IS-2000 system. However, the 1xEV-DO system allocate, to each AT, a unicast access terminal identifier (UATI) instead of an ESN and identifies each AT using the UATI. The UATI is defined for a coverage area of an identical controller (Placket Control Function (PCF) entity or Radio Network Controller (RNC)), that is, each subnet. The UATI is configured by a subnet identifier part and an AT identifier part. When a 1xEV-DO terminal moves from one subnet to another, a new UATI configured by a new subnet identifier is assigned.
Accordingly, the 1xEV-DO terminal must be first assigned a UATI corresponding to an AT identifier to exchange data with the system. The AT receiving the UATI performs a process for negotiating protocol-by-protocol system parameters of each layer to exchange data with the AN in a method for transmitting data to and receiving data from the AN through a physical layer channel, a method for setting a transmission type and a data format in a MAC layer to transmit data, a method for maintaining an established call in a connection layer or transmitting and receiving data in the idle state, a method for separating, rearranging, and retransmitting higher layer data such as a Transmission Control Protocol/Internet Protocol (TCP/IP) packet, and so on.
In the process for negotiation of the system parameters, the AT and the AN exchange a predefined message and set up a dedicated channel to exchange the message. Because the dedicated channel is set up before parameters necessary for transmission are exchanged, the AT and the AN set up a dedicated traffic channel using predetermined default parameters and perform parameter negotiation. Hereinafter, negotiated system parameters and system variable sets are defined as a session configuration. A process for negotiating this session configuration is called a session configuration procedure. The session configuration is maintained and updated during one session, that is, a period in which data communication can be performed between the AT and the AN.
The session configuration procedure between the AT and the AN is divided into an AT initiated state for sending a request for desired parameters from the AT to the AN and an AN initiated state for proposing, to the AT, parameters that the AN desires to use. The AT or AN sends a list of parameter values to be used for one system parameter through a ConfigurationRequest message. If a value desired by a side for receiving the ConfigurationRequest message is present in the parameter value list, the receiving side sends a ConfigurationResponse message containing the desired value to a transmitting side.
However, if a value desired by the receiving side for receiving the ConfigurationRequest message is absent in the parameter value list, the receiving side performs a process for sending a list of desired parameter values capable of being supported by the receiving side to the transmitting side through the ConfigurationResponse message. Then, an associated system parameter can be set to a parameter value supported between the AT and the AN. Through the above process, the AT and the AN perform parameter negotiation for all protocols to be used. A side for requesting a parameter configuration sends a ConfigurationComplete message to the receiving side and stops the session configuration process. The AT and the AN between which the session configuration is completed release the traffic channel set up by the predetermined default parameters and use newly negotiated parameters.
The conventional session configuration procedure repeats a process for releasing and reconfiguring the traffic channel whenever a new session is configured. When a parameter value for a session Configuration other than a currently applied session configuration is added while the AT and the AN perform data communication using a specific session configuration, a process for releasing the traffic channel is equally performed as descried above. However, a repeat operation for releasing and reconfiguring the traffic channel as described above results in unnecessary service delay and degrades user service satisfaction, when a parameter of a previously configured session is also used in the next session configuration process, that is, a parameter to be used is not varied,
The conventional session configuration procedure cannot delete a stored session configuration after completing negotiation between the AT and the AN. To delete a preset specific session, the AT and the AN wait for another session configuration to be negotiated and must use a method for overwriting a newly negotiated session configuration on a session configuration to be deleted. When all unnecessary session configuration is not deleted in the proper time, the AT and the AN must unnecessarily perform an operation for continuously managing an unused session configuration.
For example, this corresponds to the case where the AT moves to another subnet and a handoff is performed. In this case, the AN must receive session configuration values used in a previous subnet. Because a procedure for deleting an unnecessary session configuration is not provided in the conventional system a handoff target AN for the AT receives up to an unnecessary session configuration and therefore overhead occurs in terms of time and memory.
The conventional session configuration procedure cannot partially update stored session parameter values after completing negotiation between the AT and the AN. Accordingly, the AT and the AN must again perform a total session configuration process to update a specific session, resulting in unnecessary message transmission and reception and unnecessary waste of time.